Electrified vehicles (EV), such as battery electric vehicles (BEV) and hybrid-electric vehicles (HEV), typically include one or more electric machines mechanically coupled to a hybrid transmission. The hybrid transmission may further be mechanically coupled to a conventional engine. The electric machine is capable of operating as a motor or a generator to propel the vehicle. The electric machines may provide propulsion and deceleration capability for the EV when the engine is turned on or off. The electric machines may also act as generators, recovering mechanical energy as electrical energy. A traction battery, or battery pack, may be used to store the electrical energy, which can later be used by the electric machines.
A vehicle battery pack typically provides a high voltage direct current (DC) output, and may be electrically coupled to one or more power electronics modules. The power electronics modules may also be electrically coupled to the electric machines, and may provide bi-directionally transferable energy between the battery and the electric machines. A battery management system may include one or more controllers, such as a Battery Energy Control Module (BECM), which is typically used to monitor and control the performance of the traction battery. In normal operation, a traction battery provides a DC voltage while the electric machines operate with a three-phase alternating current (AC) to function. The power electronics module converts the DC voltage to a three-phase AC current to operate the electric machines. In a regenerative mode, the power electronics module converts the three-phase AC current from the electric machines, acting as generators, to the DC voltage compatible with the traction battery.
A lithium-ion battery is typically used in electrified vehicles, but lithium-ion batteries are not capable of accepting higher charge current than allowed by design, especially at temperatures lower than normal temperature (e.g., 25° C.). When the charging current exceeds the design limit of the battery, lithium plating may occur on the anode of battery cell, which decreases battery capacity and increases cell resistance. In some instances, the battery may need to be replaced depending on the extent of plating.